More moms are staying at home with their kids full time, and those moms tend to be younger, less educated and more likely to be poor than women who work outside the home, new research finds.

That picture of stay-at-home motherhood may be at odds with a stereotype many Americans have of wealthier, more educated mothers who choose to stay home with their children because they can afford not to work.

While that’s still true of some moms, researchers also argue that many women who stay at home are doing so at least partly because they can’t afford the child care costs and other expenses associated with going to work, especially if they can’t get a job that pays well.

D’Vera Cohn, a senior writer at Pew Research Center and one of the authors of the new report, said women who stay home with their children are likely doing so for a slew of reasons, including economic ones.

"Even women who say they're staying home by choice may tell you they're home because the workplace didn't offer them many other options," she said.

The new analysis of stay-at-home moms with children under age 18, released Tuesday by Pew Research Center, found that 29 percent of moms with kids under age 18 were stay-at-home moms in 2012, up from 23 percent in 1999.

The study, which was based on a detailed analysis of government data through 2012, appears to show that economic pressures may be one factor behind that increase. Since 2000, Cohn said there has been an increase in the share of moms who said they are at home with their kids because they can’t find a job.

The researchers also found that Hispanic, Asian and immigrant mothers are more likely than their peers to stay home full-time with children.

For many women, Cohn said there are probably a number of reasons — including economic factors, personal preferences and cultural norms — that go into the decision to stay home.

Allicyn Willix, 29, has been a stay-at-home mom since her daughter Parker, now 2, was born. She has relished the time with her kids, but she’s also looking forward to her son, Conner, starting kindergarten next fall. That’s because it will mean she only has to pay child care expenses for one child – and can afford to go back to work.

“I really want to be able to get out there and provide financially (because ) we struggle at times,” she said. “But it’s rewarding, too, to be able to stay at home.”

In general, the Pew report showed, the least-educated mothers are most likely to be at home. About 21 percent of college-educated moms are stay-at-home moms, compared with 35 percent of high school graduates and 51 percent of moms with less than a high school diploma.

The share of college-educated moms who don't work outside the home has not risen substantially since 2000.

Cohn said Pew’s research also found that only a fraction of stay-at-home moms appear to be “opting out” of high pressure careers. The researchers found that women with at least a master’s degree and a family income of more than $75,000 made up just 5 percent of married stay-at-home moms with working husbands.

“Certainly these elite stay-at-home mothers have gotten a lot of attention, but they’re only a small slice of all stay-at-home moms,” Cohn said.